BG 17.19

Penance performed out of foolishness, with self-torture or to destroy or injure others, is said to be in the mode of ignorance.

17.19. What austerity is practised with foolish obstinacy [and] with self-torture only in order to destroy other person-that is declared to be of the Tamas.

17.19 Austerity done under delusion, and accompanied with sorcery or torture to oneself or another, may be assumed to spring from Ignorance.

17.17-19 Sraddhaya etc. upto tamasam udahrtam. There is faith in all the three-fold austerity. the faith of a man of the Sattva is full of austerity itself. The faith of a man of the Rajas is in the Rajas i.e, showing (or hyprocricy) etc. But, the faith (or desire) of a man well established in the Tamas is merely in ruining others. Thus the sage speaks of all the three-fold austerity practised with faith.

17.19 Deluded persons are those who lack correct understanding. That austerity which is practised from deluded notion, viz., from the obstinate determination by deluded persons, by self-torture regardless of one's own capacity or which is performed for causing sufferings to others - that is said to be Tamasika.

17.19 Yat, that; tapah, austerity; which is kriyate, under-taken; mudha-grahena, with a foolish intent, with a conviction arising out of non-discriminating; pidaya, causing pain; atmanah, to oneself (to one's body etc.); va, or; utsadanartham, for the destruction; parasya, of another; tat, that; is udahrtam, said to be; an austerity tamasam, born of tamas. Now the classification of charity is being spoken of:

17.19 That austerity which is practised from deluded notions by means of self-torture or in order to injure another is said to be Tamasika.

17.19 That austerity which is undertaken with a foolish intent, by causing pain to oneself, or for the destruction of others-that is said to be born of tamas.